Coolant Collection Comprising a Filterdryer Unit

ABSTRACT

Disclosed is a coolant collector ( 1 ) comprising a filter/dryer unit ( 10 ) and an elongate, vertically oriented interior space which is subdivided into an upper area ( 38 ) and a lower area ( 39 ) by means of the filter/dryer unit ( 10 ). A flowing coolant is delivered to the filter/dryer unit ( 10 ) via a pipe ( 7 ). The outlet windows of the filter/dryer unit ( 10 ) are located on the outer circumference thereof which delimits a relatively narrow gap along with the wall ( 3 ) of the receptacle ( 2 ) of the coolant collector ( 1 ). Liquid components drip downwards and accumulate below the filter/dryer unit while gaseous components accumulate primarily above the filter/dryer unit ( 10 ).

The invention relates to a coolant collector comprising a filter/dryer unit for cooling systems. The coolant collector in accordance with the invention is particularly suitable for motor vehicle air-conditioning systems and, in this case, in particular for those which are operated with carbon dioxide as the coolant.

As a rule, coolants flow through coolant collectors, in which case said collectors keep a coolant supply ready. This supply buffers minor coolant losses of the refrigerating machine as well as different conditions of use of said machine. Consequently, as a rule, a certain amount of liquid coolant is present in the coolant collector. The coolant must be dry. If ice forms in the refrigerating machine at unfavorable points, this may result in disruptions of the operation of the refrigerating machine and also in damage to said machine. Consequently, as a rule, refrigerating systems comprise dryers. These are, for example, tubular storage receptacles, in which a water-absorbing material, for example, a granulate, is arranged. This granulate is perfused by the coolant, in so doing, it is critical that sufficient intimate contact between the coolant and the dryer material be ensured.

In particular the compressors of CO₂ refrigerating machines, but also the compressors of other refrigerating machines, are relatively sensitive to fluid droplets and, in particular, solid particles, that are taken in by suction. Consequently, it is desirable to reliably ensure that the sucked in stream of coolant does not contain any solid particles.

Considering this, it is the object of the invention to provide a unit which solves at least some of the aforementioned problems in a technically simple and reliable manner.

This object is achieved with the coolant collector comprising an integral filter/dryer unit in accordance with Claim 1:

The coolant collector in accordance with the invention is based on a pressure-resistant, upright receptacle having a wall, bottom and upper closure so that a closed interior space is being enclosed. A first pipe leads into the interior space, and a second pipe leads out of the interior space. Arranged inside the interior space is a filter/dryer unit, which is fed by the pipe leading into the interior space. In so doing, coolant is delivered approximately to the center of the filter/dryer unit. The filter/dryer unit comprises at least one, preferably however, several large-area outlets that have a cross-section exceeding the cross-section of the delivering pipe. The outlets terminate in the interior space of the container, in which oil, as well as liquid coolant, may collect. The pipe leading out of the interior space has an upper open end that, preferably, is located above the filter/dryer unit. Said pipe leads out of the interior space at this point. In so doing, said pipe extends, preferably in the form of a U, extends around the filter/dryer unit, whereby a lower pipe bend of the pipe leading out of the interior space extends across the bottom of the receptacle. In this region, an intake opening is preferably provided. The pipe bend undercuts an oil level which is formed in the receptacle. As a result of this, the stream of coolant leaving via the intake opening may suck up, and carry along, oil in a metered manner. This is desirable for lubricating the connected compressors.

A partial volume of the interior space is limited between the oil level and the filter/dryer unit, whereby coolant in the fluid phase may be present in said space. The amount of liquid coolant may fluctuate independent of the conditions of use of the refrigerating machine. However, the filter/dryer unit separates the coolant level from the steeply upward extending open pipe end of the pipe leading out of the interior space, so that coolant spray may not enter the open pipe end, not even when the coolant collector is installed in motor vehicles and shaken vigorously during extreme driving maneuvers or on bumpy roads.

Referring to a preferred embodiment, the wall of the receptacle of the coolant collector is cylindrical, whereas the bottom of the receptacle is rounded. The latter has the advantage that—even with minimal amounts of oil—a sufficiently high oil level can be achieved in order supply the coolant stream with oil. In addition, the shape of the receptacle is thus particularly pressure-resistant.

The upper closure of the receptacle is preferably flat or slightly rounded, whereby the two pipes are located next to each other, leading into the receptacle, as well as out of it. As a result, an approximately cylindrical steam dome is formed above the filter/dryer unit, said steam cone primarily containing coolant in the gaseous phase that can be readily drawn off. In addition, the connection of the pipes which are aligned next to each other, preferably in a parallel mariner, is simple and not complex.

Preferably, the filter/dryer unit takes up the entire cross-section of the interior space in such a manner that said unit, with the wall of the receptacle, defines only a relatively narrow annular gap. Exiting from this annular gap, the coolant moves at a relatively low flow rate as it enters the upper area acting as a steam dome. Sloshing motions of the coolant level below the filter/dryer unit hardly cause the liquid coolant to enter into the area above the filter/dryer unit. This does not occur, in particular, in view of the preferred height (axial extension) of the filter/dryer unit, which is preferably greater than the diameter of said unit.

Drops of liquid coolant and drops of oil fall downward out of the annular gap and accumulate below the filter/dryer unit. In so doing, liquid CO₂ floats onto the top of the oil level.

Basically, it is possible to draw the oil collecting under the filter/dryer unit out off the receptacle and add it to the oil stream via capillaries or separate lines. Consequently, the pipe leading out of the interior space can lead directly out of the upper steam dome region to the outside. However, a preferred simple and durable solution is to guide the pipe leading out of the interior space—as it descends, as well as it ascends—between the wail and the filter/dryer unit and thus move the coolant that has been evacuated in the upper dome region through the pipe bend, where it is mixed with oil.

Preferably, the filter/dryer unit comprises a housing having a flat upper side and an approximately cylindrical outer circumference. This unit efficiently separates the liquid coolant phase from the vaporous coolant phase. Furthermore, said unit features a sufficiently large interior space for the accommodation of a large drying agent portion.

It has been found to be highly advantageous to provide the filter/dryer unit with a conical bottom. The tip of the bottom is preferably located in the center of the housing, approximately below the feed pipe. In so doing, the cone angle is relatively large and preferably ranges between 120° and 170°. This shape of the bottom has been found to be advantageous from the viewpoint of the developing flow pattern, as well as from the viewpoint of practicality, because said shape permits good contacting of the dryer granulate when the filter/dryer unit is being closed. This is true, in particular, when the bottom is installed from the underside in the housing of the filter/dryer unit and is then fixed in place, for example, by engagement means. The dry granulate is perfused essentially in radial direction, whereby the flow rate is low and decreases toward the outside. This permits an intimate contact between the dry granulate and the coolant fluid. The low flow rate in the housing of the filter/dryer unit results in a low pressure drop across the coolant collector.

Preferably, spherical granulate bodies are used as the dry granulate, thus providing an optimal contact between the coolant and the dry granulate.

On the input side, the filter/dryer unit is provided with an inlet basket having, on its circumference and on its bottom, outlet opening, e.g., bores and slits. The inlet basket permits a delivery of the coolant fluid into the dry granulate at a low pressure drop. Preferably, a fine-mesh filter is provided at the outlet openings of the housing of the filter/dryer unit. Said filter consists, e.g., of a fine stainless steel net, a stainless steel felt or the like. The mesh size is preferably within the range of from 30 μm to 60 μm.

The conical bottom is a prerequisite to obtaining a good separation of the gaseous and liquid phases. The collection of liquid coolant and/or oil in the filter/dryer unit is avoided with certainty. As a result, the dry granulate itself is kept free of fluids, so that its effectiveness is not impaired by oil or liquid coolant.

The outlet windows take up almost the entire outer circumference of the housing of the filter/dryer unit. This has the effect of an additional efficient utilization of the drying agent due to slow perfusion as well as of a safe output of coolant fluid and oil out of the housing of the filter/dryer unit.

Additional details of advantageous embodiments of the invention are the subject matter of the description or the claims. The drawings illustrate exemplary embodiments of the invention. They show in

FIG. 1 a perspective view of the complete coolant collector;

FIG. 2 a perspective view, vertically in section, of the coolant collector in accordance with FIG. 1;

FIG. 3 a vertical sectional view of the coolant collector in accordance with FIG. 2, with an additional sectional view of its filter/dryer unit;

FIG. 4 a vertical sectional view of the filter/dryer unit of the coolant collector in accordance with FIGS. 2 and 3; and,

FIG. 5 a sectional view of a detail of the coolant collector in accordance with FIG. 1.

FIG. 1 shows a coolant collector 1 comprising an outer receptacle 2 being configured as an aluminum bottle. It has a cylindrical wall 3 with an essentially flat upper closure 4 and, for example, a spherically arched bottom 5. The bottom 5 may be provided with an opening into which a bursting plug 6 is screwed. The receptacle 2 is closed toward the outside on all its sides. It may consist of two or more welded together parts, whereby the welding seams are not shown in FIG. 1. Preferably, the receptacle 2 is made without welding or soldering seams, i.e., without welding and soldering operation. To achieve this, first a hollow cylindrical blank is produced, said blank already having the upper closure 4. After all of the later explained fixed structures have been placed in the receptacle 2, the latter is closed on its bottom 5 by means of a roll-forming operation or by another alternative reforming operation to such an extent that only the opening that is to be closed by the plug 6 remains. This manufacturing process permits the production of the receptacle 2 with a relatively low wall thickness even when it is to be designed for very high bursting pressures of, for example, above 200 bar. Other structural changes of the material that occur during welding and soldering are excluded.

Two pipes 7, 8 lead through the closure 4 into or out of the interior space 9 enclosed by the receptacle 2, as is obvious from FIG. 2. In so doing, the ends of the pipes 7, 8 extend parallel with respect to each other through the closure 4. The pipe 7 forms the intake-side line for the delivery of coolant into the coolant collector 1. It leads to a filter/dryer unit 10 which is accommodated in the interior space 9 of the separate housing 11. In so doing, the end 12 of the pipe 7 located in the interior space 9 leads to a central connection that, i.e., strictly speaking, is arranged on its preferably flat upper side 13. In addition, the housing 11 has a cylindrical outer circumference 14 with a diameter that is slightly smaller than the inside diameter of the wall 3, so that a slit is created between the two. In order to adjust this slit in a specific manner and to center the housing 11 in the receptacle 2, the outer circumference 14 is provided with radially outward projecting spacer projections 15 that are configured as ribs 16, 17, 18 preferably being vertically longitudinal, i.e., oriented in axial direction. In addition, outlet windows 19, 20, 21, 22, 23 (see FIGS. 2 and 3) are provided on the outer circumference 14, said window openings opening the interior space 24 of the housing 11—on its entire circumferential area—toward the interior spaces 9 of the receptacle 3 [sic], as is obvious from FIG. 3. The outlet windows 19 through 23 are only separated from each other by narrow strips that connect the upper closure plate located on the upper side 13 with a lower ring 25 which holds a bottom 26 set into the housing 11. The outlet windows 19 through 23 may be provided with a grid of plastic material, said grid supporting the installed, later-explained filters and providing protection against manual damage during assembly.

Preferably, the bottom 26—like the remaining housing 11—consists of plastic material. Said bottom has a conical bottom section 28 that extends upward from an annular rim 27, said bottom section having a cone angle of preferably approximately 130° to 150°. Preferably the bottom 26 is connected with the ring 25 by means of not specifically illustrated engagement means. The outer edge 29 of said bottom adjoins the upper edge of the ring 25 or is arranged just above it.

The outlet windows 19 through 23 are closed by a fine-mesh filter. The latter may be made of a stainless steel net, a stainless steel felt or the like. The mesh size is preferably in the range between 30 μm and 60 μm.

Inside the interior space 24 of the housing 11 is an inlet basket 31 that is preferably connected in one piece with the upper closure plate of the housing 11. The inlet basket 31 has a cylindrical shape, for example. On its circumference, said basket is provided with slits 32. Its bottom is provided with openings 33. Preferably, the slits 32 and the openings 33 have a width of no more than 0.8 mm. In any event, the width of the slits 32 and the openings 33, is less than the grain size of the dry granulate that fills the interior space 24. This granulate is disposed to absorb water.

The housing 11 has diametrically opposed or otherwise positioned relative locations with groove-like cutouts, preferably cutouts having approximately the form of cylindrical shells, through which extends the pipe 8. It extends from an open end located above the filter/dryer unit 10 vertically downward to the bottom 5 of the receptacle 2. The corresponding straight pipe section 34 then terminates below the filter/dryer unit 10 in a pipe bend 35, from where it leads—with another pipe section 36—again past the filter/dryer unit 10 to the closure 4 and through said closure toward the outside. The pipe bend 35 extends just above the bottom 5, as is obvious, in particular, from FIG. 5. At its deepest point, where the pipe bend 35 is the closest to the bottom 5, the pipe bend is provided with a suction bore 37. Said suction bore has a small diameter and is disposed to add oil to the coolant flowing in the pipe bend 35.

The coolant collector 1 described so far is disposed to operate as follows:

During operation, the receptacle 2 is arranged vertically, i.e., its pipes 7, 8 lead essentially vertically into the interior space 9. The center axis of the cylindrical wall extends perpendicularly. The coolant initially flows from the refrigerating machine through the pipe 7 into the filter/dryer unit that divides the interior space 9 into an upper area 38 that is disposed to act as a steam cone and into a lower area 39 that is disposed to act as a fluid collector. As a rule, the coolant is a three-phase mixture consisting of a gaseous coolant, of a liquid coolant and of liquid oil particles. This mixture first enters the inlet basket 31, then leaves it through the slits 32 and the openings 33, through which the mixture enters the densely packed, preferably spherical, dryer body. In so doing, the flow is directed through the openings 32 at the bottom section 28 which radially redirects the flow toward the outside. The result is a relatively uniform, slow perfusion of the dryer packing held in the interior space 24. Liquid components, i.e., liquid coolant and oil, reach the bottom section 28 and move along it toward the outside. They leave the filter/dryer unit 10 through the outlet windows 19 through 23 and drain downward on the ring 25 into the partial space formed by the area 39. In contrast, gaseous coolant accumulates primarily in the area 38 of the interior space 9, from were it may be drawn off through the pipe 8.

A fluid supply consisting of oil and liquid coolant is formed under the filter/dryer unit 10. As a result of their different densities, they separate from each other. This is true, in particular, when the coolant used is CO₂. Above the bottom 5, an oil volume 40 having an oil level 41 is formed; on this rests a liquid coolant volume 42 having a coolant level 43. The oil level 41 is at least above the suction bore 37. The coolant level 43 is at least below the rim 29, preferably, however, below the ring 25.

The vaporous coolant present in the area 38 flows through the pipe section 34 and the pipe bend 35, in which case it carries oil along via the suction bore 37. The suction bore 37 may also be viewed as a drainage bore which restricts the oil access into the pipe 8 to a desired low degree. If necessary, several such bores may be provided. In addition, a filter being configured, for example, as a metal net, a metal felt or the like, may be arranged between the pipe bend 35 and the bursting plug 6.

The filter/dryer unit 10 causes not only a drying of the coolant but, at the same time, a division of the interior space 9 that is so effective that no spray from the potentially boiling or sloshing—due to exterior motion—coolant volume 42 enters the open end of the pipe section 34. In this way, a simple, combined coolant collector comprising an integral filter/dryer unit 10 has been created.

A coolant collector 1 comprising a filter/dryer unit 10 comprises an elongate, vertically oriented interior space which is subdivided into an upper area 38 and a lower area 39 by means of the filter/dryer unit 10. The in-flowing coolant is delivered to the filter/dryer unit 10 via a pipe 7, said unit having its outlet windows located on its outer circumference which delimits a relatively narrow gap along with the wall 3 of the receptacle 2 of the coolant collector 1. Liquid components drip downwards and accumulate below the filter/dryer unit while gaseous components accumulate primarily above the filter/dryer unit 10. 

1. Coolant collector (1) comprising a pressure-resistant upright receptacle (2) having a wall (3), a bottom (5) and an upper closure (6) which enclose an interior space (9); a pipe (7) leading into an interior space (9), said pipe having an end (12) located in the interior space (9); a filter/dryer unit (10) that is connected to the end (12) of the pipe (7) leading into the interior space (9), said end being located in the interior space (9); and, a pipe (8) leading out of the interior space (9), said pipe having an open end located above the filter/dryer unit (10) accommodated in the interior space (9).
 2. Coolant collector in accordance with claim 1, characterized in that the pipe (8) leading out of the interior space (9) extends from its open end to a pipe bend (35) located on the bottom (5) and, ascending therefrom, from the receptacle (2), whereby the pipe bend (35) is provided with at least one suction opening (37).
 3. Coolant collector in accordance with claim 1, characterized in that the wall (3) of the receptacle (2) is cylindrical.
 4. Coolant collector in accordance with claim 1, characterized in that the bottom (5) of the receptacle (2) is rounded.
 5. Coolant collector in accordance with claim 1, characterized in that the upper closure (4) of the receptacle (2) is flat, and that the two pipes (7, 8) lead next to each other into or out of the receptacle (2).
 6. Coolant collector in accordance with claim 1, characterized in that the filter/dryer unit (10) takes up the entire cross-section of the interior space (9) and defines an annular gap with the wall.
 7. Coolant collector in accordance with claim 1, characterized in that the pipe (8) leading out of the interior space (9) is guided—as it ascends, as well as it descends—between the wall (3) and the filter/dryer unit (10).
 8. Coolant collector in accordance with claim 1, characterized in that the filter/dryer unit (10) comprises a housing (11) having a flat surface (13) and having an approximately cylindrical outer circumference (14), from which extend spacer projections (15) toward the wall in order to abut against said wall.
 9. Coolant collector in accordance with claim 1, characterized in that the filter/dryer unit (10) has a conical bottom (26).
 10. Coolant collector in accordance with claim 1, characterized in that the filter/dryer unit (10) has, on its upper side (13), a central connection which is connected to the pipe (7) that leads into the interior space (24).
 11. Coolant collector in accordance with claim 10, characterized in that the filter/dryer unit (10) encloses a receiving space (24) in which an inlet basket (31) having inlet openings (32, 33) is arranged, said inlet basked directly adjoining the central connection.
 12. Coolant collector in accordance with claim 11, characterized in that, referring to the filter/dryer unit (10), the inlet openings are configured as holes (33) or as slits (32) having a width that is not greater than the grain size of the dryer granulate.
 13. Coolant collector in accordance with claim 1, characterized in that the filter/dryer unit (10) has outlet windows (19, 20, 21, 22, 23) on its outer circumference.
 14. Coolant collector in accordance with claim 13, characterized in that, referring to the filter/dryer unit (10), the outlet windows (19, 20, 21, 22, 23) take up almost the entire outer circumference of the filter/dryer unit (10).
 15. Coolant collector in accordance with claim 13, characterized in that the outlet windows (19, 20, 21, 22, 23) of the filter/dryer unit (10) are provided with a filter (30).
 16. Coolant collector in accordance with claim 1, characterized in that the filter (30) of the filter/dryer unit (10) consists of a fine-mesh stainless steel net.
 17. Coolant collector in accordance with claim 1, characterized in that the filter/dryer unit (10) comprises a housing (11) made of plastic material.
 18. Coolant collector in accordance with claim 17, characterized in that the filter/dryer unit (10) has a bottom that is locked to the remaining housing (11).
 19. Coolant collector in accordance with claim 1, characterized in that the filter/dryer unit (10) is arranged at approximately half the height of the interior space (9) or above.
 20. Coolant collector in accordance with claim 21, characterized in that the suction opening (37) is located on the underside of the pipe bend (35) facing the bottom (5). 